Transmission of pictures by electricity



Patented. my 14, 1925.

UNITED STATES 1,545,708 PATENT OFFICE.

DONALD M. TERRY, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC cou- PANY, INCORPORATED, OF NEW YORK, N. Y-, A CORPORATION OF NEW YORK.

TRANSMISSION 01 PICTURES BY ELECTRICITY.

Application filed my a, 1924. Serial No. 711,740

To all whom it may concern:

Be it known that I, DONALD M. TERRY,

a citizen of the United States of America,

residing at New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Transmission of Pictures by Electricity, of which the following is. a full, clear, concise, and exact description.

This invention relates to the transmission of pictures by electricity and more particularly to means for controlling the reproducing process.

In the transmission of pictures by elec tricity by means of sending and reproducing drums and intermediate transmission equipment, it is not only necessarj to drive the drums in exact synchronism but it is'equally important to start them simultaneously. One arrangement for accomplishing this result in a sim 1e manner is disclosed in a copending app ication of M. B. Long, Serial No. 681,347, filed DecemberlS, 1923. In the Long arrangement, the light valve is operated by demodulated current from an electron discharge demodulator and the same current is used to energize the control apparatus. As disclosed ina copendin application of E. C. Wente, Serial No. 01,016, filed March 22, 1924, an improved reproducing arrangement comprises a light valve upon which the modulated tcarrier wave is di- "rectly impressed and which functions itself asa demodulator. When such a light valve is employed, the Long control arrangement is not suitable,

The object of this invention is to accom effective manner.

According to one embodiment of the invention, the last discharge device at the re producing terminal functions as an ampli fier to impress modulated carrier current on the light valve for'picture reproduction and as a detector to control the release mechanism of the reproducing 'drum for starting the process of reproduction. The changeover is effected by remote control of the carrier current at the sendin terminal.

The novel features which are considered characteristic of this invention are set forth with particularity in the appended claims. The invention, both as to 1ts organization same time by the rotation of shaft 6. The

shaft 6 is driven by means of friction drive .7. At the reproducing terminal, reproducin drum 1s similarly rotated and moved axially by the rotation of shaft 51 which is driven by friction drive 52. Both shafts may be rotated in either direction by individual' reversible motors (not shown). A suitable driving and synchronizing system is disclosed in the Long application supra.

Referring now to Fig. 1, a transparency 8 of the picture to be transmitted is mounted on the sending drum 5. Light from source 9 is concentrated by means of lens 10, upon a small area of the transparency 8. Light from source 9 passes through the transparency 8 and the transparent drum 5 into photo electric cell P, where it determines the amount of current flowing from battery 11 and consequently the otential impressed upon the input circuit 0 picture amplifier PA. Current from a source of carrier wave C is impressed upon a modulator M by way of conductor 12, contact 13 of switch S, and conductor 14. This carrier wave is modulated by the picture current in the modulator M from the output of which modulated current is impressed'upon the line L through filter SPF b way of conductor 100 which it is im ressed upon the input cir- 105 cuit of reproducing amplifier-detector RA D. The output circuit of receiving amplifier-detector RA-D is connected through conductor 54, contact 55 of relay 53, and conductor 56' to one terminal of the primary winding .ofitransformer 57. The other. terminal of this winding is connected through conductor 58, tothe positive terminal of plate battery 61. The other terminal of battery 61 is connected to the cathodes of the electron discharge devices and to ground. The secondary winding of transformer 57 is directly connected to string 62v of light valve V.

The vibration of string 62 controls the exposure of a light sensitive record blank 63 mounted on reproducing drum 50 by light.

from source 64 through. lenses 65 and 66.

For-the transmission of a icture line L of Fig. 1 is associated with me L of Fig. 2 through a circuit which is capable of transmitting voicefrequency currents. This connection may be through an ordinary telephoneiline, a carrier telephone channel or a radiotelephone channel. In the circuit as shown, it is assumed tha a picture is in the process of being trans-' mitted. The motors driving shafts 6 and 51 are rotating in such a direction as to cause axial motion of' the drums 5 and 50 in the direction indicated by the arrows. The rotation of drum 5 with its transparencyf 8ijof the picture to. be transmitted,

causes-the carrier wave from'sourceC to be modulated with ithe pictureLcharacteristics in 'ill rilodulator Asthe drum '5 moves in ithe ldirection of the arrow, it will eventually enga .stop ipg; key 18, cl0sing a contact whi'e ,icompetes'a circuit through battery 19, relay 20andright hand contact of stop-.

. 'iqThe' sha e of the notc'hindis'c 23 is clearly shown in'Fig. 3. From that'figure, itis "closure of key 6 v jthrough battery 68, relay 69 -a nd;le ft hand contact of stopping switch 70. Theener .zation of i'elay69attracts its armature causingit s engagement with disc--72 tostop r "the rotation of. shaft 51. Thearmature'71l isjnormally held in retractedpbeition by.

;.p ing1switchf:21. The ene 'gization of, relay 20, attracts its armature "-22 which "engages with a notch in detent disc 23 to stoptheretation of shaft 6.' Thearmature-22 isnor mally in retracted pQsitio by'spring clearthat the armature 22 when inat tract'ed position willprevent the rotation of -shaft 6 in either direction. zgsimultaneously with the closing of sto ping key 18 at the transmitting terminal, t e reproducing drum will engage stopping key 67 at the re rod-ucing terminal. The will complete a circuit sprin'g i73; The action ofari'iiatiire 71 in [serving-as a detent for,disc-;72-'will be"clear descriptionthereof.

- fi'omaq 'reference to Fig. 3 and the previousa The transmitting prdblaiik fiii may now-be removed from'reruin 50 and developed in well is outgoing on the line L these conditions, relay 7 recess is thusautomaticallyli stopped. e" light sensitive rec-- f The "procedure of transmitting another picture or the same picture over again will now be described! The trans arency of the picture to be transmitted is mounted on sending drum 5. Starting key S is thrown to the left in which position contacts 13 and 16 are opened and contacts 25 and 26 are closed. The closure of contact 25 completes a circuit for relay 20 independently of the con tacts of stopping key 18 and the right hand of contact 26 completes a circuit for car- 'rier waves from source C to line L independently of the'modulator M by way of circuitcompletedat oldingswitch 75 and sliaft51'isfprevented from rotating by de'-' tent 71. Starting'switch74 which is preferably a non-locking key, is closed long ,enough toenerg'lze rela 53 over' a circuit including resistance 76, attery'61 d m da tior 60. q a

1 Theenergization of relay 53 converts the ,receivingamplifier-detector RA-D from an amplifier to a detector by substituting negative grid polarizing battery 79 of 40 volts in lace. of battery 17 of- 9 volts potential. attery 79 is connected inseries with the whole of resistance81 at contact 80 'ofrelay 53,-before battery 77 is disconnected from the upper part of resistance 81 at contact 59 of relay 53.. The upper part of resistance 81 has preferably a resistance of 7500 ohms and the lower part, 200,000 ohms. During the change-over,-therefore, batteries 77 and 79 are connected in op osing relationship inseries with 200,000 0 ms, so that-no excessive-'crirr'ehtsare present. The grid circuitof the amplifier-detector RA-D is thus never without. i;.a negative'polarizing potential and large surges-of plate current are thus not present during the change-over, as would be the caselwere the battery 77 disconnected from the grid before the battery 79 was applied thereto or viceversa. Vere 'Such surge not obviated, special precautions would need to be taken to insure that the 'light valve V was 'firstdisconnected, otherwise it would be thrown out of adjustment.

The energization of relay 53 also1discon ght handpos tion;

contact of stopping switch 21. The closure conductor 27, contact 28 of test switch T, contact 26 of switch S, and conductor 17. Stopping switch 21 is then closed in its left energization of rela 82 completes an energizing circuit for re y 69 at contact 85 independently of holding switch 75. It also completes a circuit for relay 53 at contact a 86 independently of starting key 74. As

soon as starting key S (at the sending'terminal) is thrownto its left hand position and the startin key 74 (at the reproducing terminal) has een closed to energize relay 53, holding key 75 at the reproducing terminal may be opened. The system is now in condition to start the transmission of another picture. The driving motors, if not already rotating, are started in such a direction as to cause the drums5 and 50 to move in a direction opposite to that indicated by the arrows.

To start the operation, the starting key S isfirst thrown to normal position in which condition each of the contacts 13, 16, 25 and 26 is open. The opening of contact 25, deenergizes relay 20 and releases shaft 6. The opening of contact 26 interrupts the flow of carrier waves to the line'L. At contacts 13 and 16, the input and output circuits of the modulator are interrupted. At the reproducing terminal the interruption of incoming carrier waves releases relay 82 and opens contacts 85 and 86 thereof. The opening of contact 85, deenergizes magnet 69 and releases shaft 51. The opening of contact 86 deenergizes relay 53' and converts the receiving amplifier-detector RA-D from a detector to an amplifier by substituting battery 77 for battery 79.

Starting switch S is then thrown to its right hand position and the process of transmitting the picture continues in the manner hereinbefore described. When the picture surface has been traversed, drum 5 engages stopping key 29 and drum 50 engages stopping key 87 to automatically stop the drums in a manner similar to that described in connection with stopping keys 18 and 67.

To'transmit another picture, the process is repeated except that the direction of rotation of the driving motors is such that the drums 5 and 50 move again in the direction indicated by the arrows.

Condenser 88 is provided to improve the detecting action of the receiving amplifierdetector RA-D. The resistance capacity networks 89 and 90, connected respectively in shunt of contacts 85 and 86, are provided to obviate sparking disturbances when these contacts are opened at the start of the transmission process. v

An effective control arrangement is thus provided which operates with the drums moving in either direction. The last tube acts as an amplifier for picture transmission and as a detector for starting the transmission process. The starting of the reproducing equi ment is remote controlled from the sending station over the same carrier channel that is normally used for transmitting the picture characteristics.

Electron discharge devices are preferably employed and their use is schematically indicated in the drawing. The filters SPF and RPF are designed according to the principles set forth in Campbell Patent- No. 1,227,113, May 22, 1917 and serve the purpose disclosed in the Long application supra.

Various modifications of the specific em-- bodiment of the invention which has been described may be made without departing from the scope of the invention as defined in. the appended claims. I

What I claim is:

1. In a system for the transmission of pictures by electricity comprising terminal stations and apparatus at each station for the transmission of pictures, the method which compries normally transmitting carrier waves from one station to the other, detecting said carrier waves, at one station to delay the transmitting process, interrupting the transmission of carrier waves from the second station to start the picture transmissionprocess at the first stat-ion, simultaneously starting the picture transmitting process at the second station, and amplifying the carrier waves at the first station where before they were detected.

2. In a system for recording intelligence, a movable record blank, a source of carrier waves modulate-d with the characteristics of the intelligence -to be recorded, an amplifier for amplifying carrier waves from said source, 'means to record said intelligence from said amplifiedwaves, and means to convert said amplifier into a detector to control the movement of said movable record blank.

3. In a system for reproducing pictures I from electricity, a movable light sensitive record blank. a source of carrier waves modulated with the characteristics of the picture to be reproduced, an optical arrangement for exposing said record blank to reproduce the picture, an amplifier for carrier waves from said source for impressing amplified waves upon said optical arrangement, and switching means to convert said amplifier into a detector to control the movement of said movable record blank.

4. In a system for reproducing pictures from electricity, a reproducing drum, means to rotatesaid drum, a light sensitive record blank mounted on said drum, a source of carrier waves modulated with the characteristics of the picture to be reproduced, an elec- Y &

tro-magnetic light valve and optical arrange ment for exposing said record blank, an amplifier for amplifying modulated carrier waves from said carrier source and impress ing the amplified waves upon said light valve, and switching means to convert said amplifier into a detector to control the rotation of said drum. I

5. In a system for the transmission of pictures by electricity, a reproducing drum, a light sensitive record blank mounted on said drum, means to rotate said drum, a source of carrier waves modulatcdwith the characteristics of the picture to be reproduced, an amplifier for amplifying carrier waves from said source, means to expose said record blank in accordance with demodulated current from said amplified waves, means to prevent the rotation of said drum, a relay arranged when energized to cause saidmeans including a movable element for reproducing the picture, means to detect the carrier waves from said source to control the movement of said movable element, and means to convert said detecting means. to amplifying means to amplify the modified carrier waves for energizing said reproducing means. 7

. 7. In a system for transmitting pictures by electricity, a source of carrier waves, means including a movable element for modifying carrier waves from said source in accordance with the elements of a picture to be successively transmitted, restraining means to prevent the movement of said movable element, means including a second movable element for reproducing the picture, a second restraining means to prevent the movement of said second movable ele-' ment, means to detect carrier waves from said source to control said second restraining means, means to convert said detecting means to amplifying means toamplify the modified carrier waves for energizing said reproducing means, and starting means to control both said first restraining means and carrier waves from said source.

8. Ina system for'the transmission of pietures by electricity, a source of carrier waves, means including a movable clement tomodify carrier waves from said source in accordance with the elements of the picture to be successively transmitted, means including a second movable element for reproducing the picture, separate restraining means to prevent the movement of said movable elements, means to detect carrier waves from said source to control one of said restraining means, means to convert said detccting means to amplifying means to ampllfy the modifiedcarrier waves for energizmg sa1d reproducing means, and means for simultaneously controlling carrier waves from said source and said other restraining means. v

9. In a system for the transmission of pictures by electricity, a source of carrier waves, means to modify carrier waves from said source in accordance with the elements of a picture to be successively transmitted, means including a movable element for reproducing the picture, means to detect carrier waves from said source. to control the movement of said movable element, means to convert said detecting means to amplifying. means to amplify the modified carrier waves for energizing said reproducing means, said converting means including means to prevent reconverting said amplifying means to detecting means by subsequent changes-in the character of the carrier waves.

10. In a system for the transmission of pictures by electricity, a circuit over which carrier waves are received, a reproducingv drum," a light valve, an electron'discharge detector, means to lock said reproducing drum in response to the receipt of carrier waves by said detector, means to unlock said drum due to an interruption in the receipt of carrier waves and simultaneously to convcrt said electron discharge detector into an electron discharge amplifier.

-1-1. In a system for the transmission of pictures by electricity, a. circuit over which carrier waves are received, a reproducing drum, a light valve, an electron discharge, I

detector, means to lock said reproducing drum in response to the receipt of carrier waves by said detector,"'means to unlock said drum due to an interruption in the receipt of carrier waves and simultaneously to convert said electron discharge detector'into an electron discharge amplifier, and means to' prevent a subsequent locking'of said reproducmg drum when carrler waves are again received.

12. In a system for the transmission of glzcd 'by current from said detector and pictures by electricity, a circuit over which carrier waves are received, a reproducing adapted when carrier current is being received to cause the relay locking circuit to lock the drum and further adapted when carrier current is interrupted to unlock the drum and to simultaneously convert the detector into an amplifier.

13. In' a system for the transmission of pictures by electricity, a circuit over which earner waves are recelved, a reproducing fit Eroducing drum,

nuance drum and furt er adapted when carrier current is interrupted to unlock the drum and to simultaneousl convert the detector into an amplifier, an a third relay controlled by said second relay for converting said detector into an amplifier and open-circuiting the energizing winding of the second relay so that it will not be energized when carrier waves are again received.

14. In a' system for the transmission of pictures by electricity, a transmission circuit,'a source of voice frequency carrier waves of one frequency, a sending drum, a transparency of the picture mounted on said drum, a photo-electric cell within said drum, an amplifier for amplifying picture currents flowing throu h said photo-electric cell an electron disciarge modulator to modulate said carrier waves in accordance with said amplified picture currents and to impress modulated waves upon said transmission circuit, a reproducing drum, a light valve, an electron discharge detector actuated by carrier current fromv said'transmis sion circuit, a circuit including means for locking said sending drum in stationary position and for connecting said source to said transmission circuit, either inde ndently of or through said modulator an for 'disconnecting said source-from said transmission 3 circuit, -means' to lock said reproducing drum in res onse to detected carrier waves received in ependentl of said modulator, means to unlock said rum due to interruptions in the received carrier waves and to simultaneously convert said detector into an amplifier for actuating said light valve toreproduce the icture, and means to prevent a subse uent ocking of said reproducing drum w en carrier waves are again received.

15'. In a system for the transmission of pictures by electricity,'a circuit over which carrier waves are received, a reproducing drum, a light valve,'a three-electrode electron discharge detector, a source of negative polarizing potential for said detector, a rela circuit to control the rotation of the repro ucing drum, a second relay adapted to connect a source of lower negative polarizing potential to said vdetector before dis a third relay energized by current from said detector and adapted when current is being received to cause the relay drum control circult to cause the drum to remaln stationary and further adapted when carrier current is interrupted to cause rotation ofthe drum and to simultaneously control said second In witness whereof, I ereunto -connecting said'first mentioned source, and

subscribe my name this 29th day of April A, D., 1924.

DONALD. M. TERRY. Q a 

